#include <fstream>
#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <cstdio>

#define LOCAL_DEBUG 1

#if LOCAL_DEBUG
char input_file[] = "data.in";
#define INPUT in
#else
#define INPUT cin
#endif // LOCAL_DEBUG

using namespace std;

///////////////////////////////////////////////////////////
// Sample Input Data:
// 4 1
// 2 5
// 3 5
// 8 7
///////////////////////////////////////////////////////////

typedef vector<double> array1d;
typedef vector<array1d> array2d;

inline unsigned int gen_sub_alphabeta_set(unsigned int* alphabeta_set,
                                          unsigned int  a, 
                                          unsigned int  k)
{
    unsigned int num = 0;
    
    if (a == 0) 
    {
        alphabeta_set[0] = a;
        alphabeta_set[1] = a + 1;
        num = 2;
    }
    else if (a == k)
    {
        alphabeta_set[0] = a - 1;
        alphabeta_set[1] = a;
        num = 2;
    }
    else
    {
        alphabeta_set[0] = a - 1;
        alphabeta_set[1] = a;
        alphabeta_set[2] = a + 1;
        num = 3;
    }
    
    return num;
}

double calc_num_of_tight_words(unsigned int k,
                               unsigned int n)
{
    unsigned int        num_of_alphabet = k + 1;
    unsigned int        sub_alphabeta_set[3];
    unsigned int        sub_alphabeta_num;
    double              num_of_tight_words = 0.0;
    array2d             lut(num_of_alphabet);

    for(unsigned int a = 0; a < num_of_alphabet; a++)
    {
        lut[a].resize(n);
        lut[a][0] = 1.0;
    }

    for(unsigned int len = 1; len < n; len++)
    {
        for(unsigned int a = 0; a < num_of_alphabet; a++)
        {
            sub_alphabeta_num = gen_sub_alphabeta_set(sub_alphabeta_set, a, k);
            for(unsigned int s = 0; s < sub_alphabeta_num; s++)
            {
                lut[a][len] += lut[sub_alphabeta_set[s]][len-1];   
            }
        }
    }
    
    for(unsigned int a = 0; a < num_of_alphabet; a++)
    {
        num_of_tight_words += lut[a][n-1];
    }

    return num_of_tight_words;
}

int main(void)
{
    unsigned int k;
    unsigned int n;
    
#if LOCAL_DEBUG
    ifstream in(input_file);
#endif // LOCAL_DEBUG
    
    while((INPUT>>k>>n) && !INPUT.eof())
    {
        double num_of_words = 0.0;
        double num_of_tight_words = 0;
        
        num_of_words = pow((double)(k+1), (double)n);
        
        if (k == 0)
        {
            num_of_tight_words = 1.0;
        }
        else
        {
            num_of_tight_words = calc_num_of_tight_words(k, n);
        }
        
        cout<<setiosflags(ios::fixed)<<setprecision(5)<<(num_of_tight_words/num_of_words)*100.0<<endl;
    }
    
    return 0;
}
